.\"	$NetBSD: umask.2,v 1.6 1995/02/27 12:39:06 cgd Exp $
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.\"     @(#)umask.2	8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt UMASK 2
.Os BSD 4
.Sh NAME
.Nm umask
.Nd set file creation mode mask
.Sh SYNOPSIS
.Fd #include <sys/stat.h>
.Ft mode_t
.Fo umask
.Fa "mode_t cmask"
.Fc
.Sh DESCRIPTION
The
.Fn umask
routine sets the process's file mode creation mask to
.Fa cmask
and returns the previous value of the mask.
The 9 low-order access permission bits of
.Fa cmask
are used by system calls, including
.Xr open 2 ,
.Xr mkdir 2 ,
.Xr mkfifo 2 ,
and
.Xr mknod 2
to turn off corresponding bits
requested in file mode.
(See
.Xr chmod 2 ) .
This clearing allows each user to restrict the default access
to his files.
.Pp
The default mask value is S_IWGRP | S_IWOTH (022, write access for the
owner only).
Child processes inherit the mask of the calling process.
.Sh RETURN VALUES
The previous value of the file mode mask is returned by the call.
.Sh ERRORS
The
.Fn umask
function is always successful.
.Sh LEGACY SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/stat.h>
.Pp
The include file
.In sys/types.h
is necessary.
.Sh SEE ALSO
.Xr chmod 2 ,
.Xr mkdir 2 ,
.Xr mkfifo 2 ,
.Xr mknod 2 ,
.Xr open 2 ,
.Xr compat 5
.Sh STANDARDS
The
.Fn umask
function call is expected to
conform to 
.St -p1003.1-88 .
